ScaFi: A scalable bio-inspired robotic fish for aquatic research

Engineers have developed ScaFi, a bio-inspired robotic fish designed to scale in size without requiring a complete redesign. Led by Nana Obayashi, the project addresses a common limitation in underwater robotics where traditional propeller-driven vehicles often disturb sediment, snag on vegetation, or startle aquatic wildlife.

Unlike most fish-inspired robots that are built for a single specific task or size, ScaFi utilizes a design modeled after fish like cod and mackerel. The robot features a rigid front section and a flexible tail made of fiberglass rods. A single motor operates a crossed-tendon system to create an 'S'-shaped swimming motion. To scale the robot for different environments, such as moving from shallow creeks to larger lakes, only the diameter of the tail rods needs to change, allowing the motor mechanism and tendon system to remain consistent.